Chapter 24 Evolution and Speciation

Question 1

What is a species?

Answer 1

Group of populations whose members have the potential to interbreed in nature and produce viable. fertile offspring

Question 2

What is the morphological species concept?

Answer 2

Defines a species by structural features

Question 3

What are the limitations of biological species?

Answer 3

• Biologists can’t apply it to those who only reproduce asexually
• Gene flow does occur b/w species

Question 4

Reproductive Isolation

Answer 4

Existence of biological factors (barries) that impede two species from producing successful offspring

Question 5

Hybrids

Answer 5

Offspring of crosses b/w different species

Question 6

What are some reproductive isolation barries?

Answer 6

• prezygotic barrier (before fertilization)
• postzygotic barrier (after fertilization)

Question 7

What are the prezygotic barriers (5 things)

Answer 7

• habitat isolation: Differences in habits
• Temporal isolation: breeding seasons are different
• behavioral isolation: Changes in courting
• mechanical isolation: morphological differences
• gametic isolation: sperm of one species may not fertilize egg of another

Question 8

What are the postzygotic barriers? (3 things)

Answer 8

• reduced hybrid viability: Hybrids are not likely to survive and reproduce
• reduced hybrid fertility: Hybrids are physically fit but are sterile
• Hybrid breakdown: First-generation of hybrids are fertile but their offspring are sterile or feeble

Question 9

What are the 2 types of speciation?

Answer 9

• allopatric speciation
• sympatric speciation

Question 10

allopatric speciation

Answer 10

speciation in which populations live in different geographical areas and can’t move

Question 11

sympatric speciation

Answer 11

speciation in which populations live in the same geographical area but the populations are isolated due to uses of different parts of the habitats

Question 12

What are the different forms of speciation by polyploidy? (5 things)

Answer 12

• Polyploidy: presence of extra sets of chromosomes due to accidents during cell division
• Haploid: n, one genome of chromosomes (23 in humans)
• Diploid: 2n, 2 genomes of chromosomes (46 in humans)
• Autopolyploid: All genomes are from one species
• Allopolyploid: Species with multiple sets of chromosomes derived from different species

Question 13

What is speciation?

Answer 13

Origin of new species, in which it’s at the focal point of evolutionary history

Question 14

What is macroevolution?

Answer 14

Broad patterns of evolutionary changes above the species level

Question 15

What is microevolution?

Answer 15

Consists of changes in allele frequencies in a population over time

Question 16

What is the ecological species concept?

Answer 16

Views species in terms of its ecological niche

• applies to sexual and asexual species and emphasizes the role of disruptive selection

Question 17

What is phylogenetic species concept?

Answer 17

Defines a species as the smallest group of individuals on a phylogenetic tree

• also applies to sexual and asexual species

Question 18

What can sexual speciation do?

Answer 18

It can derive sympatric speciation

Question 19

What is habitat differentiation?

Answer 19

Sympatric speciation can also results from this as the appearance of new ecological niches

Question 20

What is a hybrid zone?

Answer 20

A region in which members of different species mate and produce hybrids

• can cause reproductive isolation

Question 21

What are the 3 possible outcomes for a hybrid zone?

Answer 21

• reinforcement: Reinforcement of reproductive prezygotic barriers
• Fusion: Weakening of reproductive barriers
• stability: continued formation of hybrid individuals

Question 22

How can speciation occur?

Answer 22

Can occur both slow and fast as a result of few or many genetic changes